The invention relates to a biodegradable disposable diaper provided with a liquid permeable bodyside inner liner and an at least substantially liquid impermeable outer layer, which form a front panel and a rear panel, with a liquid-absorbent batt sandwiched between the inner liner and the outer layer.
It is noted that the term disposable diaper in this context is not only understood to mean a disposable device which is provided on small children's bodies for collecting urine and feces therein, but also a disposable device in particular for incontinent adults.
A disposable diaper is known from International Patent Application No. WO 84/04242 (Johnson & Johnson Products, Inc.). The disposable diaper of International Patent Application No. WO 84/04242 has a synthetic outer layer of polyethylene and a non-woven synthetic inner liner, with a batt of a fluff-like cellulosic material sandwiched therebetween.
A drawback of the known disposable diaper is that it is very environment-unfriendly because of its use of synthetic materials. The production of such a diaper requires the use of materials which are harmful to the environment. The processing into waste of the diaper causes serious harm to the environment. The fact of the matter is that in addition to the fact that the known disposable diapers, which comprise a synthetic outer layer and a synthetic inner liner will lie on a mountain of waste for a considerable period of time, they generate noxious ash remnants plus gases (CO.sub.2 emission) upon being incinerated. The problem described herein is certainly not an imaginary one, in view of the enormous scale on which the known disposable diapers are being used. In order to overcome the above-mentioned drawback a so-called "diaper service" has already been proposed. This "diaper service", is based on the distribution of clean cotton diapers of the time-honored type to users who are members of this "diaper service", collecting and cleaning used cotton diapers from such users and subsequently distributing the cleaned, used cotton diapers again, etc. Although the "diaper service" enjoys a growing popularity, a large part of the diaper users have a continued need for disposable diapers.
U.S. Pat. No. 5,207,664 (Blanco) is related to a disposable diaper formed of biodegradable materials, which includes an outer fabric sheet coextensively and adherably mounted to a fibrous underlying sheet, with a fluid absorbing fabric matrix mounted medially of the fibrous sheet and an inner porous sheet mounted coextensively to the fabric matrix web utilizing heat activated adhesive for securement of the layers together. The outer fabric sheet is formed of a natural fiber, such as cotton.
U.S. Pat. No. 3,683,917 (Comerford) is directed to a sanitary towel comprising a cellulosic absorbent core, a cellulosic covering material and a biodegradable, water impervious barrier sheet comprising a water repellent tissue, whereby use is made of a hydrocolloidal material being capable of swelling in body fluids and cooperating with the repellent tissue to form an impervious barrier to body fluids.
U.S. Pat. No. 5,026,363 (Pratt) relates to a flushable diaper comprising, in combination, a three layered combined structure configured as a lightweight, small bikini bottom, having a top layer, a middle layer and a bottom layer. The bottom layer is made of a breathable, hydrophobic material of the kind sold by DuPont under the trademark "EVLON" which consists of 40% polyester fiber and 60% calcium carbonate. The middle layer comprises a wood pulp type material in order to be capable of absorbing a relatively large amount of liquid waste. The top layer is a material selected from at least one of the group consisting of cotton and rayon in order to provide a thin moisture permeable, biodegradable layer.
U.S. Pat. No. 5,185,009 (Sitnam) describes a biodegradable diaper comprising an outer sheet of biodegradable material able to resist water absorption, an inner sheet of biodegradable material able to allow the passage of water and attached to the outer sheet by a biodegradable adhesive at the periphery to form an envelope, a super absorbent core within the envelope, and a water resistant film of biodegradable material located within the core to assist in fluid distribution into the core. The outer sheet is of rayon, whereas the inner sheet is of polyethylene. The biodegradable adhesive is a natural rubber latex, whereby the core may be a sulphite cooked pulp subjected to a hammer mill.
None of the above patent publications discloses or suggests to a person skilled in the art a disposable diaper according to the claims of the present application. None of the disposable diapers proposed according to the above-described U.S. Patents have become a success, either because the materials required by them make the resultant product too expensive, or because they exhibited urine leakage, due to the layers not being strong enough in a wet condition. In particular these drawbacks have been overcome by the proposed disposable diaper according to the present application, which has resulted in resounding commercial success.